aboutsummaryrefslogtreecommitdiffstats
path: root/fs/ecryptfs/file.c
blob: 9881b5c5de59b6f564435cc26dc17f5a638e32bc (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
/**
 * eCryptfs: Linux filesystem encryption layer
 *
 * Copyright (C) 1997-2004 Erez Zadok
 * Copyright (C) 2001-2004 Stony Brook University
 * Copyright (C) 2004-2007 International Business Machines Corp.
 *   Author(s): Michael A. Halcrow <mhalcrow@us.ibm.com>
 *   		Michael C. Thompson <mcthomps@us.ibm.com>
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License as
 * published by the Free Software Foundation; either version 2 of the
 * License, or (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful, but
 * WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA
 * 02111-1307, USA.
 */

#include <linux/file.h>
#include <linux/poll.h>
#include <linux/mount.h>
#include <linux/pagemap.h>
#include <linux/security.h>
#include <linux/compat.h>
#include <linux/fs_stack.h>
#include "ecryptfs_kernel.h"

/**
 * ecryptfs_llseek
 * @file: File we are seeking in
 * @offset: The offset to seek to
 * @origin: 2 - offset from i_size; 1 - offset from f_pos
 *
 * Returns the position we have seeked to, or negative on error
 */
static loff_t ecryptfs_llseek(struct file *file, loff_t offset, int origin)
{
	loff_t rv;
	loff_t new_end_pos;
	int rc;
	int expanding_file = 0;
	struct inode *inode = file->f_mapping->host;

	/* If our offset is past the end of our file, we're going to
	 * need to grow it so we have a valid length of 0's */
	new_end_pos = offset;
	switch (origin) {
	case 2:
		new_end_pos += i_size_read(inode);
		expanding_file = 1;
		break;
	case 1:
		new_end_pos += file->f_pos;
		if (new_end_pos > i_size_read(inode)) {
			ecryptfs_printk(KERN_DEBUG, "new_end_pos(=[0x%.16x]) "
					"> i_size_read(inode)(=[0x%.16x])\n",
					new_end_pos, i_size_read(inode));
			expanding_file = 1;
		}
		break;
	default:
		if (new_end_pos > i_size_read(inode)) {
			ecryptfs_printk(KERN_DEBUG, "new_end_pos(=[0x%.16x]) "
					"> i_size_read(inode)(=[0x%.16x])\n",
					new_end_pos, i_size_read(inode));
			expanding_file = 1;
		}
	}
	ecryptfs_printk(KERN_DEBUG, "new_end_pos = [0x%.16x]\n", new_end_pos);
	if (expanding_file) {
		rc = ecryptfs_truncate(file->f_path.dentry, new_end_pos);
		if (rc) {
			rv = rc;
			ecryptfs_printk(KERN_ERR, "Error on attempt to "
					"truncate to (higher) offset [0x%.16x];"
					" rc = [%d]\n", new_end_pos, rc);
			goto out;
		}
	}
	rv = generic_file_llseek(file, offset, origin);
out:
	return rv;
}

/**
 * ecryptfs_read_update_atime
 *
 * generic_file_read updates the atime of upper layer inode.  But, it
 * doesn't give us a chance to update the atime of the lower layer
 * inode.  This function is a wrapper to generic_file_read.  It
 * updates the atime of the lower level inode if generic_file_read
 * returns without any errors. This is to be used only for file reads.
 * The function to be used for directory reads is ecryptfs_read.
 */
static ssize_t ecryptfs_read_update_atime(struct kiocb *iocb,
				const struct iovec *iov,
				unsigned long nr_segs, loff_t pos)
{
	int rc;
	struct dentry *lower_dentry;
	struct vfsmount *lower_vfsmount;
	struct file *file = iocb->ki_filp;

	rc = generic_file_aio_read(iocb, iov, nr_segs, pos);
	/*
	 * Even though this is a async interface, we need to wait
	 * for IO to finish to update atime
	 */
	if (-EIOCBQUEUED == rc)
		rc = wait_on_sync_kiocb(iocb);
	if (rc >= 0) {
		lower_dentry = ecryptfs_dentry_to_lower(file->f_path.dentry);
		lower_vfsmount = ecryptfs_dentry_to_lower_mnt(file->f_path.dentry);
		touch_atime(lower_vfsmount, lower_dentry);
	}
	return rc;
}

struct ecryptfs_getdents_callback {
	void *dirent;
	struct dentry *dentry;
	filldir_t filldir;
	int err;
	int filldir_called;
	int entries_written;
};

/* Inspired by generic filldir in fs/readir.c */
static int
ecryptfs_filldir(void *dirent, const char *name, int namelen, loff_t offset,
		 u64 ino, unsigned int d_type)
{
	struct ecryptfs_crypt_stat *crypt_stat;
	struct ecryptfs_getdents_callback *buf =
	    (struct ecryptfs_getdents_callback *)dirent;
	int rc;
	int decoded_length;
	char *decoded_name;

	crypt_stat = ecryptfs_dentry_to_private(buf->dentry)->crypt_stat;
	buf->filldir_called++;
	decoded_length = ecryptfs_decode_filename(crypt_stat, name, namelen,
						  &decoded_name);
	if (decoded_length < 0) {
		rc = decoded_length;
		goto out;
	}
	rc = buf->filldir(buf->dirent, decoded_name, decoded_length, offset,
			  ino, d_type);
	kfree(decoded_name);
	if (rc >= 0)
		buf->entries_written++;
out:
	return rc;
}

/**
 * ecryptfs_readdir
 * @file: The ecryptfs file struct
 * @dirent: Directory entry
 * @filldir: The filldir callback function
 */
static int ecryptfs_readdir(struct file *file, void *dirent, filldir_t filldir)
{
	int rc;
	struct file *lower_file;
	struct inode *inode;
	struct ecryptfs_getdents_callback buf;

	lower_file = ecryptfs_file_to_lower(file);
	lower_file->f_pos = file->f_pos;
	inode = file->f_path.dentry->d_inode;
	memset(&buf, 0, sizeof(buf));
	buf.dirent = dirent;
	buf.dentry = file->f_path.dentry;
	buf.filldir = filldir;
retry:
	buf.filldir_called = 0;
	buf.entries_written = 0;
	buf.err = 0;
	rc = vfs_readdir(lower_file, ecryptfs_filldir, (void *)&buf);
	if (buf.err)
		rc = buf.err;
	if (buf.filldir_called && !buf.entries_written)
		goto retry;
	file->f_pos = lower_file->f_pos;
	if (rc >= 0)
		fsstack_copy_attr_atime(inode, lower_file->f_path.dentry->d_inode);
	return rc;
}

struct kmem_cache *ecryptfs_file_info_cache;

int ecryptfs_open_lower_file(struct file **lower_file,
			     struct dentry *lower_dentry,
			     struct vfsmount *lower_mnt, int flags)
{
	int rc = 0;

	flags |= O_LARGEFILE;
	dget(lower_dentry);
	mntget(lower_mnt);
	*lower_file = dentry_open(lower_dentry, lower_mnt, flags);
	if (IS_ERR(*lower_file)) {
		printk(KERN_ERR "Error opening lower file for lower_dentry "
		       "[0x%p], lower_mnt [0x%p], and flags [0x%x]\n",
		       lower_dentry, lower_mnt, flags);
		rc = PTR_ERR(*lower_file);
		*lower_file = NULL;
		goto out;
	}
out:
	return rc;
}

int ecryptfs_close_lower_file(struct file *lower_file)
{
	fput(lower_file);
	return 0;
}

/**
 * ecryptfs_open
 * @inode: inode speciying file to open
 * @file: Structure to return filled in
 *
 * Opens the file specified by inode.
 *
 * Returns zero on success; non-zero otherwise
 */
static int ecryptfs_open(struct inode *inode, struct file *file)
{
	int rc = 0;
	struct ecryptfs_crypt_stat *crypt_stat = NULL;
	struct ecryptfs_mount_crypt_stat *mount_crypt_stat;
	struct dentry *ecryptfs_dentry = file->f_path.dentry;
	/* Private value of ecryptfs_dentry allocated in
	 * ecryptfs_lookup() */
	struct dentry *lower_dentry = ecryptfs_dentry_to_lower(ecryptfs_dentry);
	struct inode *lower_inode = NULL;
	struct file *lower_file = NULL;
	struct vfsmount *lower_mnt;
	struct ecryptfs_file_info *file_info;
	int lower_flags;

	mount_crypt_stat = &ecryptfs_superblock_to_private(
		ecryptfs_dentry->d_sb)->mount_crypt_stat;
	if ((mount_crypt_stat->flags & ECRYPTFS_ENCRYPTED_VIEW_ENABLED)
	    && ((file->f_flags & O_WRONLY) || (file->f_flags & O_RDWR)
		|| (file->f_flags & O_CREAT) || (file->f_flags & O_TRUNC)
		|| (file->f_flags & O_APPEND))) {
		printk(KERN_WARNING "Mount has encrypted view enabled; "
		       "files may only be read\n");
		rc = -EPERM;
		goto out;
	}
	/* Released in ecryptfs_release or end of function if failure */
	file_info = kmem_cache_zalloc(ecryptfs_file_info_cache, GFP_KERNEL);
	ecryptfs_set_file_private(file, file_info);
	if (!file_info) {
		ecryptfs_printk(KERN_ERR,
				"Error attempting to allocate memory\n");
		rc = -ENOMEM;
		goto out;
	}
	lower_dentry = ecryptfs_dentry_to_lower(ecryptfs_dentry);
	crypt_stat = &ecryptfs_inode_to_private(inode)->crypt_stat;
	mutex_lock(&crypt_stat->cs_mutex);
	if (!(crypt_stat->flags & ECRYPTFS_POLICY_APPLIED)) {
		ecryptfs_printk(KERN_DEBUG, "Setting flags for stat...\n");
		/* Policy code enabled in future release */
		crypt_stat->flags |= ECRYPTFS_POLICY_APPLIED;
		crypt_stat->flags |= ECRYPTFS_ENCRYPTED;
	}
	mutex_unlock(&crypt_stat->cs_mutex);
	lower_flags = file->f_flags;
	if ((lower_flags & O_ACCMODE) == O_WRONLY)
		lower_flags = (lower_flags & O_ACCMODE) | O_RDWR;
	if (file->f_flags & O_APPEND)
		lower_flags &= ~O_APPEND;
	lower_mnt = ecryptfs_dentry_to_lower_mnt(ecryptfs_dentry);
	/* Corresponding fput() in ecryptfs_release() */
	if ((rc = ecryptfs_open_lower_file(&lower_file, lower_dentry, lower_mnt,
					   lower_flags))) {
		ecryptfs_printk(KERN_ERR, "Error opening lower file\n");
		goto out_puts;
	}
	ecryptfs_set_file_lower(file, lower_file);
	/* Isn't this check the same as the one in lookup? */
	lower_inode = lower_dentry->d_inode;
	if (S_ISDIR(ecryptfs_dentry->d_inode->i_mode)) {
		ecryptfs_printk(KERN_DEBUG, "This is a directory\n");
		crypt_stat->flags &= ~(ECRYPTFS_ENCRYPTED);
		rc = 0;
		goto out;
	}
	mutex_lock(&crypt_stat->cs_mutex);
	if (!(crypt_stat->flags & ECRYPTFS_POLICY_APPLIED)
	    || !(crypt_stat->flags & ECRYPTFS_KEY_VALID)) {
		rc = ecryptfs_read_metadata(ecryptfs_dentry, lower_file);
		if (rc) {
			ecryptfs_printk(KERN_DEBUG,
					"Valid headers not found\n");
			if (!(mount_crypt_stat->flags
			      & ECRYPTFS_PLAINTEXT_PASSTHROUGH_ENABLED)) {
				rc = -EIO;
				printk(KERN_WARNING "Attempt to read file that "
				       "is not in a valid eCryptfs format, "
				       "and plaintext passthrough mode is not "
				       "enabled; returning -EIO\n");
				mutex_unlock(&crypt_stat->cs_mutex);
				goto out_puts;
			}
			rc = 0;
			crypt_stat->flags &= ~(ECRYPTFS_ENCRYPTED);
			mutex_unlock(&crypt_stat->cs_mutex);
			goto out;
		}
	}
	mutex_unlock(&crypt_stat->cs_mutex);
	ecryptfs_printk(KERN_DEBUG, "inode w/ addr = [0x%p], i_ino = [0x%.16x] "
			"size: [0x%.16x]\n", inode, inode->i_ino,
			i_size_read(inode));
	ecryptfs_set_file_lower(file, lower_file);
	goto out;
out_puts:
	mntput(lower_mnt);
	dput(lower_dentry);
	kmem_cache_free(ecryptfs_file_info_cache,
			ecryptfs_file_to_private(file));
out:
	return rc;
}

static int ecryptfs_flush(struct file *file, fl_owner_t td)
{
	int rc = 0;
	struct file *lower_file = NULL;

	lower_file = ecryptfs_file_to_lower(file);
	if (lower_file->f_op && lower_file->f_op->flush)
		rc = lower_file->f_op->flush(lower_file, td);
	return rc;
}

static int ecryptfs_release(struct inode *inode, struct file *file)
{
	struct file *lower_file = ecryptfs_file_to_lower(file);
	struct ecryptfs_file_info *file_info = ecryptfs_file_to_private(file);
	struct inode *lower_inode = ecryptfs_inode_to_lower(inode);
	int rc;

	if ((rc = ecryptfs_close_lower_file(lower_file))) {
		printk(KERN_ERR "Error closing lower_file\n");
		goto out;
	}
	inode->i_blocks = lower_inode->i_blocks;
	kmem_cache_free(ecryptfs_file_info_cache, file_info);
out:
	return rc;
}

static int
ecryptfs_fsync(struct file *file, struct dentry *dentry, int datasync)
{
	struct file *lower_file = ecryptfs_file_to_lower(file);
	struct dentry *lower_dentry = ecryptfs_dentry_to_lower(dentry);
	struct inode *lower_inode = lower_dentry->d_inode;
	int rc = -EINVAL;

	if (lower_inode->i_fop->fsync) {
		mutex_lock(&lower_inode->i_mutex);
		rc = lower_inode->i_fop->fsync(lower_file, lower_dentry,
					       datasync);
		mutex_unlock(&lower_inode->i_mutex);
	}
	return rc;
}

static int ecryptfs_fasync(int fd, struct file *file, int flag)
{
	int rc = 0;
	struct file *lower_file = NULL;

	lower_file = ecryptfs_file_to_lower(file);
	if (lower_file->f_op && lower_file->f_op->fasync)
		rc = lower_file->f_op->fasync(fd, lower_file, flag);
	return rc;
}

static ssize_t ecryptfs_sendfile(struct file *file, loff_t * ppos,
				 size_t count, read_actor_t actor, void *target)
{
	struct file *lower_file = NULL;
	int rc = -EINVAL;

	lower_file = ecryptfs_file_to_lower(file);
	if (lower_file->f_op && lower_file->f_op->sendfile)
		rc = lower_file->f_op->sendfile(lower_file, ppos, count,
						actor, target);

	return rc;
}

static int ecryptfs_ioctl(struct inode *inode, struct file *file,
			  unsigned int cmd, unsigned long arg);

const struct file_operations ecryptfs_dir_fops = {
	.readdir = ecryptfs_readdir,
	.ioctl = ecryptfs_ioctl,
	.mmap = generic_file_mmap,
	.open = ecryptfs_open,
	.flush = ecryptfs_flush,
	.release = ecryptfs_release,
	.fsync = ecryptfs_fsync,
	.fasync = ecryptfs_fasync,
	.sendfile = ecryptfs_sendfile,
};

const struct file_operations ecryptfs_main_fops = {
	.llseek = ecryptfs_llseek,
	.read = do_sync_read,
	.aio_read = ecryptfs_read_update_atime,
	.write = do_sync_write,
	.aio_write = generic_file_aio_write,
	.readdir = ecryptfs_readdir,
	.ioctl = ecryptfs_ioctl,
	.mmap = generic_file_mmap,
	.open = ecryptfs_open,
	.flush = ecryptfs_flush,
	.release = ecryptfs_release,
	.fsync = ecryptfs_fsync,
	.fasync = ecryptfs_fasync,
	.sendfile = ecryptfs_sendfile,
};

static int
ecryptfs_ioctl(struct inode *inode, struct file *file, unsigned int cmd,
	       unsigned long arg)
{
	int rc = 0;
	struct file *lower_file = NULL;

	if (ecryptfs_file_to_private(file))
		lower_file = ecryptfs_file_to_lower(file);
	if (lower_file && lower_file->f_op && lower_file->f_op->ioctl)
		rc = lower_file->f_op->ioctl(ecryptfs_inode_to_lower(inode),
					     lower_file, cmd, arg);
	else
		rc = -ENOTTY;
	return rc;
}